Overview Bovine besnoitiosis is a vector-transmitted disease caused by the protozoan parasite Besnoitia besnoiti. The disease spreads from one animal to another by insect vectors—specifically, biting flies such as Tabanus and Stomoxys. All cattle breeds, independent of sex or age, can be infected.

Signs Cattle can show severe clinical signs of the disease, whereas infected sheep are often asymptomatic. Affected cattle can experience different stages of the disease with a range of symptoms including skin thickening and swelling, hair loss, and skin necrosis; bulls can become infertile. In severe cases, the disease can lead to the animal’s death.

Cysts (200–600 µm in diameter) are found in the subcutaneous tissue, fascia, and mucosa of infected animals and can survive for over 10 years in the host animal.

Human health risk It does not appear that besnoitiosis presents a zoonotic risk.

Epidemiology Bluetongue, or catarrhal fever, is caused by a double-stranded RNA virus of the genus Orbivirus and family Reoviridae. It is a noncontagious disease transmitted by insects to wild and domesticated ruminants, especially sheep.

Signs Seven or eight days after infection, sheep develop acute signs—high temperature, lethargy, and self-isolation from the herd. Shortly after the rise in temperature, the buccal mucosa becomes red and swollen, and large volumes of foamy saliva are produced. The tongue swells up and in some cases turns blue (hence the name of the disease). The crown of the unguis becomes red and painful. Affected animals can limp and ewes may abort. In most cases, growth is retarded and there is coat loss. Severely affected sheep may die eight to 10 days into the infection.

In cattle and goats, the infection is usually asymptomatic. When there are signs in cattle, the most common are hyperthermia, abortion towards the end of gestation (in the eighth month), edema (of the udders, teats, vulva, and hocks), and erythema (mucosa, teats, and udders).

The spread of BTV Bluetongue was first reported in 1876 in South Africa. While it used to be believed that is was confined to Africa, over the last 10 years the disease has spread to Asia, the southern United States, Australia, and southern Europe. A total of 24 different serotypes of the bluetongue virus are known, of which eight have been reported in Europe (serotypes 1, 2, 4, 6, 8, 9, 11, and 16).

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Overview BCV is an enveloped, single-stranded, positive-sense RNA virus belonging to the Coronaviridae family that causes intestinal and respiratory infections in ruminants worldwide. Infection can cause winter dysentery in adult animals, as well as calf enteritis and enzootic pneumonia complex in calves. Bovine coronavirus is transmitted via the oral-fecal or respiratory routes, and infected animals will typically shed the virus in their feces, particularly during parturition.

BCV may also reproduce in the upper respiratory tract, causing reoccurring respiratory or gastrointestinal infection in an animal. Infected wild ruminants have the potential to transmit the disease to domestic ruminants.

Bovine Herpesvirus 4 (BoHV-4) is a gammaherpesvirus ubiquitous of bovine. It belongs to the Rhadinovirus genus. Some strains are implicated in ocular and respiratory affections (conjunctivitis, rhinitis, tracheitis, pneumonia). Other strains have been isolated in genital affections (orchitis, epididymitis, vaginitis, abortion, metritis, mastitis) and in disorders associated with the digestive tract (glossitis, enteritis, tumors of the rumen). Distribution is worldwide and the virus infects a range of ruminants, including bison, buffalo, sheep, and goats.

Epidemiology Mycoplasmas—most of which are host-specific—cause chronic diseases that progress slowly in humans and animals. The bacterium Mycoplasma agalactiae is a common pathogen of small ruminants and is of major importance in veterinary medicine. In ovines this disease is always due to M. agalactiae, but other Mycoplasma species, M. mycoides and M. capricolum, can cause a similar disease in goats.

SignsMycoplasma agalactiae is the causative agent of contagious agalaxia, the main form of mycoplasmosis in European ovines and caprines that has a serious impact on the dairy industry. Antibiotics often fail to eradicate these infections, and in food animals mycoplasmosis is responsible for substantial economic losses.

Transmission Infection is often oral or mammary, with an incubation period ranging from two weeks to two months.

Closely Related to M. agalactiaeM. bovis, which is closely related to M. agalactiae, causes respiratory and mammary pathology in bovines and is also important in economic terms (causing calf pneumonia, mastitis, and arthritis). These two pathogens induce similar signs in their respective hosts, and they are difficult to differentiate using conventional diagnostic methods because they are so closely related.

Epidemiology Bovine respiratory syncytial virus is a pneumovirus belonging to the Paramyxoviridae family. It is closely related to human RSV, which often infects the airways of children. Both are single-stranded RNA enveloped viruses. In bovines, RSV causes respiratory infections in young animals and dairy cows. The virus is mainly present in the lower airways (the lobes of the lungs), where it damages ciliated epithelial cells that normally protect the lung against microbial invasion. RSV infection often leads to secondary bacterial infection, notably with Pasteurella haemolytica and Corynebacterium pyogenes.

Signs The signs of the disease are hyperthermia, coughing, nasal and ocular discharge, anorexia, and dyspnea (if the disease is progressing towards fatal pneumonia). In dairy cows, milk production falls off.

Transmission RSV is transmitted by direct contact through nasal secretions, and its spread is favored by proximity, for example in winter stabling, and as a result of licking in the milking room.

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Overview TSEs are infectious diseases of the brain that affect animal species in various forms, such as bovine spongiform encephalopathy (BSE, affecting cattle), scrapie (affecting goats and sheep) and chronic wasting disease (CWD, affecting deer). The diseases are caused by altered prion proteins that are resistant to chemicals and heat, and are very difficult to decompose biologically, often surviving in soil for several years.

The diseases are reported worldwide, with BSE found most frequently in Europe and CWD being most prevalent in North America. TSEs cause a slow degeneration of the central nervous system that ultimately leads to the death of an animal, and there is often a significant lapse of time between an animal becoming infected with the disease and displaying the first symptoms. As an example, at the point of infection, cattle may not show clinical symptoms for up to 6 years, and sheep may not show signs for up to 4 years.

Transmission of BSE in cattle occurs through ingestion of feed containing contaminated bone and meat meal. Transmission does not appear to occur naturally between cattle, though some evidence suggests there may be a maternally associated risk for calves born to infected cows. While pathogenesis details are unknown, studies have shown that after the agent enters the animal through oral exposure, it replicates in the Peyer's patches of the ileum and migrates to the central nervous system via peripheral nerves.

Signs Clinical signs of TSEs are often subtle and may include nervousness, aggression, low head carriage, ataxia, tremors and increased sensitivity to touch (hyperesthesia). Animals may also have a reluctance to be milked and experience weight loss and diminished milk production.

Human health risk Humans can develop a form of TSE known as Creutzfeldt-Jakob disease (CJD) by consuming food products that have been contaminated with BSE. Initiatives are in place to remove high-risk bovine tissue from the human food chain, and for products containing bovine proteins (cosmetics, pharmaceuticals, etc.), measures have been instituted to help ensure that raw materials are sourced from BSE-free regions.

Economic impact TSEs can contribute to significant economic losses, whether it be culling of animals linked to BSE or scrapie cases, the destruction of Specified Risk Material (SRM) derived from ruminants (cattle, sheep, and goats), or the impact that export restrictions in affected areas may have on the meat industry as a whole.

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Overview Bovine tuberculosis is a respiratory disease caused by the bacterium Mycobacterium bovis. It is a major infectious disease found worldwide in domestic animals, particularly cattle, as well as in certain wildlife populations.

Airborne transmission is the primary pathway for infection of M. bovis within and between species; however, animals may also become infected if they ingest large quantities of the bacterium.

Signs Bovine tuberculosis is predominantly a respiratory disease affecting the lungs and associated lymph nodes. Infection is often subclinical, while clinical signs, when present, are not specifically distinctive of the disease. Symptoms may include physical weakness, anorexia, emaciation, enlargement of lymph nodes, and coughing, particularly in advanced cases of bovine tuberculosis.

Human health risk Bovine tuberculosis is a significant zoonosis and presents a serious health risk to humans. The bacterium can be spread from animals to humans through aerosols, or through the consumption of unpasteurized milk or dairy products from infected cows.

Economic impact An outbreak of bovine tuberculosis may have a significant negative impact on the farming industry as a result of reduced milk yields, culling of herds, and restrictions on meat exports from affected areas.

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Epidemiology The BVD virus is a small, single-stranded RNA virus belonging to the genus Pestivirus. Two other animal viruses belong to this genus, namely the viruses that cause border disease (BD) in sheep and classical swine fever (CSF) in pigs.The virus that causes bovine viral diarrhea (BVD) was first identified in 1946. The disease is found throughout the world and its prevalence among animals exposed to the virus ranges from 30–80% in different countries and regions.

BVD impacts fertility in the herd The infection compromises the herd's fertility and induces the return of heat following death of the embryo when the cow is infected between the first and second months of gestation. Abortion and birth defects are possible throughout gestation.

BVD-PI animals serve as a reservoir of infection A common consequence of prenatal infection by members of this viral genus is the birth of infected offspring that are permanently immunotolerant (BVD-persistent infection (BVD-PI)), which disseminate the virus throughout the herd. BVD-PI animals (i.e., those infected between the second and the fourth months of gestation) carry the virus throughout their lifetime and constantly secrete large numbers of viral particles. This group therefore constitutes a major source of infection for the rest of the herd. In addition, BVD-PI animals sooner or later develop the fatal form of BVD called mucosal disease (MD). The number of BVD-PI animals in an infected herd is of the order of 1% (although the percentage can be as high as 27%) and detecting them is primordial in the control of Pestivirus disease.

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Overview Brucellosis is an infectious disease caused by Brucella bacteria. Brucella species of major concern are B. abortus, primarily affecting cattle; B. melitensis, primarily affecting sheep and goats; and B. suis, primarily affecting pigs. All these Brucella species are non–host-specific and may be transmitted to other animal species or humans under appropriate conditions.

Brucellosis is commonly transmitted to susceptible animals by direct contact with infected animals or in an environment that has been contaminated with discharge from infected animals. Brucellosis is thus a herd or flock problem.

Brucellosis is a notifiable disease, and any occurrence of it has to be reported to the local health authority. Depending on the species and the infection rate, different eradication programs are effective. Where incidence rates are high, vaccination programs are necessary to lower the infection rate. Once this has been achieved, surveillance programs linked to slaughter of infected animals are introduced. These programs lead to "Brucellosis-Free" and "Officially Brucellosis-Free" status for specified regions or whole countries. In Europe, surveillance is regulated in the EU Directive 2003/99/EC on monitoring of zoonoses.

Occasionally, animals may recover after a period of time. More commonly, however, the symptoms disappear but the disease prevails. Such asymptomatic animals are dangerous sources of infection.

Human health risk Raw milk and unpasteurized cheese represent the most frequent sources of human infection. Farmers and veterinary staff run an increased risk of infection due to direct exposure to aborted infected materials. In humans, the disease is not usually fatal, but if untreated, it can last for many years.

The incubation period is usually one to three weeks, but can sometimes be as long as several months. Patients show nonspecific symptoms such as undulating fever, chills, malaise, and headache.

Economic impact Brucellosis is a major public and animal health problem in many regions of the world. Although it rarely kills infected animals, considering the economic damage the disease can cause, brucellosis is one of the most serious livestock diseases worldwide.

This zoonosis has been or is close to being eradicated from a number of countries, but it is still prevalent in the Mediterranean region, Africa, Asia, and South America.

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In bulls, the contamination occurs without causing symptoms, but the infectious agent often survives for years in the lining of the foreskin.

The infection can be transmitted during intercourse with infected semen. This infection can cause significant economic losses because it causes fertility problems and infectious abortions in domestic sheep, goats, and cattle.

Bovine genital campylobacteriosis is a notifiable disease (2012 OIE List) and is considered to have socio-economic implications for public health and, in particular, international trade in animals and products of animal origin.

In ruminants, chlamydiosis is a contagious disease caused by a bacterium that also infects birds and humans. It can cause abortion, premature delivery, pneumonia, conjunctivitis, and arthritis in ruminants. The infection can be transmitted to the newborn, young, or adult ruminant by the large numbers of bacteria excreted in fetal envelopes and fluids, feces, urine, and milk, although the main route of infection is via the inhalation of contaminated aerosols. Chlamydia taxonomy was revised by Everett in 1999. In the new classification, the species are divided between two main genera:

Epidemiology Q (Query) fever is an ubiquitous zoonosis that is found throughout the world (apart from New Zealand). It is caused by Coxiella burnetii, an obligate intracellular bacterium that can infect many different animal species, including ruminants, dogs, cats, birds, and arthropods as well as humans. In ruminants (which are believed to be the main reservoir for human infection), the disease is mainly associated with reproductive dysfunction. It usually remains asymptomatic and is not usually screened for unless an animal has aborted several times or shows reproductive problems. Coxiella burnetii colonizes the placenta and causes premature delivery, low birth weight, and abortion.

Impact of Q fever on humans The main route of infection in humans is through the inhalation of contaminated aerosols, but pregnant women should not drink unpasteurized milk or consume dairy products made with untreated milk. Q fever often goes unnoticed because it can be mistaken for an influenza-like syndrome. The consequences can be dramatic in pregnant women (abortion or premature delivery) and in immunodeficient subjects or patients with valvular heart disease.

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Overview Cryptosporidiosis is caused by microscopic intestinal parasites that are excreted through the feces of an infected animal. Found throughout the world, the parasites commonly interact with other enteropathogens to produce diarrhea and intestinal injury in neonatal farm animals such as piglets, kids, lambs, and foals.

Studies have shown that concurrent infections with other pathogens such as coronavirus and rotavirus can result in more severe diarrhea. While mortality rates in cryptosporidiosis are usually low, it can be fatal when complicated by other factors such as an animal experiencing energy deficit as a result of low colostrum or milk intake, concurrent infections, or chilling caused by adverse weather conditions.

Transmission of the disease may occur directly from animal to animal, or indirectly from environmental contamination, fecal contamination of the water or feed supply, or human transmission. Infection in calves can be detected as early as 5 days of age, with diarrhea occurring between 5 and 15 days of age.

In small ruminants, infection can be associated with severe outbreaks of diarrhea, resulting in high mortality rates in lambs 4–10 days of age, and goat kids 5–21 days of age.

Although cryptosporidiosis is not generally regarded as an important enteric pathogen in pigs, infections can be seen over a broader age range (1 week of age to market age), and can contribute to postweaning malabsorptive diarrhea in infected pigs.

Cryptosporidiosis is less prevalent in foals, but when infections do occur, it is typically at 5–8 weeks of age.

Signs Signs of cryptosporidiosis can include diarrhea that persists for several days, significant weight loss, emaciation, apathy, anorexia, and dehydration.

Human health riskCryptosporidium can be a common nonviral cause of diarrhea in immunocompetent persons (e.g., children) and can have a severe health impact on immunocompromised persons. Infected animals can transmit the disease directly to humans, and there is also a risk of cryptosporidiosis being transmitted through surface and drinking water that has been contaminated with the feces of an infected animal.

OverviewEscherichia coli is a bacterial cause of diarrhea in calves, and there are at least two distinct types of diarrheal disease associated with different strains of the organism. One type has two virulence factors associated with the production of diarrhea, and fimbrial antigens such as K99 or F41 enable them to colonize villi of the small intestine.

These enteropathogens, also known as attaching and effacing E. coli, may produce verotoxins that contribute to more severe hemorrhagic diarrhea. The infection can reside in the colon, cecum, and distal small intestine, with severe infections causing edema, mucosal erosions, and ulceration.

Transmission routes include respiratory aerosol, fecal aerosol, and oral–fecal. Healthy carrier cattle may periodically excrete the organism in feces, and under the stress of parturition, excretion may increase. These conditions can lead to infection of the udder and perineum of the dam, along with contaminated calving environments. Alternately, the presence of several scouring calves can severely contaminate a calf-rearing area.

Signs K99-bearing E. coli can cause the sudden onset of profuse diarrhea in calves that are typically <5 days old, resulting in calves becoming depressed and recumbent. Calves may experience significant weight loss (>12% of body weight), and potentially hypovolemic shock and death within 24 hours.

Human health risk Cattle can be a reservoir for verotoxic E. coli serotypes associated with human hemolytic uremic syndrome and hemorrhagic colitis. Infection can occur through the consumption of contaminated food, but enteric livestock pathogens can also be transmitted to humans via direct contact that may occur during visits to petting zoos, farm tours, or livestock fairs.

Epidemiology EHD is a vector-borne infectious disease caused by a virus belonging to the Orbivirus genus of the Reoviridae family (like the bluetongue virus). Between eight and 10 different serotypes have been identified.

Transmission The virus is more-or-less exclusively transmitted by the bite of a small hematophagous dipteran of the genus Culicoides in the Ceratopogonidae family. The vector becomes infected when it feeds on an infected animal and then the virus replicates until it reaches the density necessary for transmission to another susceptible animal.

Signs The EHD virus can infect bovines and cause signs similar to those of bluetongue (i.e., fever, erosive lesions and ulcers of the oropharyngeal mucosae, stiffness, collapse, and cutaneous edema). In gestating cows, infection can induce abortion or hydranencephaly if the infection appears between 70 and 120 days of gestation.

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Overview FMD is a highly contagious viral disease that affects all cloven-hoofed animals, and is widespread throughout the world. FMD cannot be differentiated clinically from other vesicular diseases such as swine vesicular disease (SVD).

The virus is a member of the genus Apthovirus in the family Picornaviridae. There are seven serotypes of FMD virus: O, A, C, SAT 1, SAT 2, SAT 3, and Asia 1. Infection with any one serotype does not confer immunity against other serotypes.

Of the domesticated species, cattle, pigs, sheep, and goats are susceptible to FMD.

Signs Clinical signs of FMD are the appearance of vesicles (small blisters) on the feet, in and around the oral cavity, and on the mammary glands of females. Vesicles can also occur inside the nostrils and at pressure points on the limbs, especially in pigs.

Transmission generally occurs through contact between infected and susceptible animals. The virus can be excreted into the air during the acute phase of infection.

Human health risk It does not appear that FMD presents a zoonotic risk.

Economic impact The presence of FMD is a very important economic threat to the livelihood of the livestock industry due to the culling of herds and the restriction on meat exports from affected areas.

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Epidemiology IBR is caused by a herpes virus (BHV-1), which infects the respiratory tract, causing problems on these channels (tracheitis and rhinitis), fever, abortions and infertility. It can cause death when the disease spreads rapidly within a herd. IBR is transmitted by direct contact through respiratory, eye and genital secretions.

IBR virus has an immunosuppressive effect and little infection predispose the host to a secondary bacterial infection. The infection can be latent: although primary infection may seem healed, the virus is still present in the lymph nodes and can be reactivated to spread throughout the body.

Incidence and prevalence Although the incidence and prevalence of the disease vary in different continents, it is present worldwide and almost 50% of all flocks of adult cattle have already been exposed.

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Overview Leptospirosis occurs worldwide, and while the disease is typically reported in tropical climates, it can also be found in temperate climates during periods of rainfall. Leptospirosis most commonly affects pigs, cattle, and horses, and displays a variety of clinical effects ranging from mild infection to organ failure to death.

The disease is prevalent in wild mammals, but is often only noticed when the wildlife serve as an infection source for domestic animals and livestock. Leptospirosis can be transmitted transplacentally or venereally, but most often through direct contact with infected milk, urine, or placental fluids.

Signs The signs of leptospirosis can vary greatly depending upon a herd’s immunity, age of an infected animal, and the infecting serovar. In respect to infecting serovars, there are >220 pathogenic serovars of Leptospira that can cause leptospirosis.

As an example, cattle are the maintenance host for Leptospira hardjo-bovis, which can affect an animal’s kidneys, resulting in long-term urinary shedding. L. hardjo-bovis is also associated with persistent reproductive tract infections that can cause infertility in cattle.

For other Leptospira serovars such as grippotyphosa, icterohaemorrhagiae, or pomona, cattle become incidental hosts for the disease and may display various clinical signs such as lethargy, jaundice, fever, anemia, and red urine. While adult cattle do not usually die from leptospirosis, the disease can be fatal to calves and may affect pregnant cows, causing abortion, stillbirth, and the birth of weak calves.

Human health risk Leptospirosis is considered to be zoonotic, and can be transmitted to humans if a person comes in contact with water or soil that has been contaminated by urine or body fluids of an infected animal.

Economic impact The infertility that can result from persistent reproductive tract infections is perhaps the most economically damaging aspect of leptospirosis.

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Mycoplasma bovisis a member of the Mycoplasma genus of bacteria, found.. it Causes a chronic disease causing long-term losses to dairy and beef producers, and potentially resulting in severe disease and significant welfare issues. Mycoplasma bovis causes a constellation of diseases, including mastitis in dairy cows, arthritis in cows and calves, pneumonia in calves, and various other diseases likely including late-term abortion. Not all infected cows get sick – some shed the disease without becoming ill, allowing for transmission between farms if these cows are moved. Mycoplasma bovis does not cause disease in humans. It does not cause severe disease in animals besides cattle, although it can cause rare mild infections in sheep, goats, and other related species.

EpidemiologyNeospora caninum is a protozoan parasite first observed in dogs, in which it causes myositis and encephalitis. However, in the 1990s it was observed that Neospora was a major cause of abortion in cows, usually between the fourth and seventh months of gestation. Depending on the number of infected cows in the herd, the abortion rate ranges from 5–30%; the higher rates are characterized by serial abortions occurring in less than a month.

Transmission It is not fully understood how the parasite is transmitted, but the main route seems to be from mother to offspring, with at least 80% of the calves born to seropositive cows infected. In addition, it has been suggested that dogs may be involved in the transmission of Neospora to bovines. This infection is known on all continents and is the leading cause of bovine abortion in some countries (ahead of BVD and IBR).

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Epidemiology Parainfluenza virus type 3 (PI3) is an RNA virus belonging to the Paramyxoviridae family, which is extremely common in livestock throughout the world. PI3 has been detected in both respiratory and digestive conditions, and it causes respiratory problems in young bovines. PI3 is also considered a cofactor in conditions associated with infection by certain bacteria (Mycoplasma bovis and Pasteurella haemolytica), and other viruses (including those that cause BVD and IBR).

Signs The signs of the disease are hyperthermia, coughing, ocular and nasal discharge, anorexia, dyspnea, and diarrhea. PI3 is also immunosuppressive, and infected animals are predisposed to secondary infections.

Transmission PI3 is usually transmitted in nasal secretions, and its transmission is favored by animal transport (direct contact, poor ventilation, and a stagnant atmosphere). To confirm PI3 infection, serological testing is strongly recommended.

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Overview Paratuberculosis, also known as Johne’s disease, is caused by the presence of Myobacterium avium spp. paratuberculosis (sometimes abbreviated MAP) in the small intestine of ruminants. It is a worldwide animal health problem, especially affecting beef and dairy herds.

Paratuberculosis is a chronic debilitating enteritis, and its presence in an animal herd can have serious effects on production.

Diagnosis of clinical infection is usually confirmed by the demonstration of the causal organism, M. avium ssp. paratuberculosis, in feces or in intestinal tissues postmortem. The identification of subclinical disease in animals, which can shed the organism over long periods and thus be the source of infection for other members of a herd, is more difficult. The prevalence of bovine paratuberculosis in Europe varies from country to country, ranging from 7% to 55%.

Signs Chronic inflammation of the intestine, mesenteric lymph node lesions, diarrhea, weight loss, and edema usually appear in animals of over 2 years of age with an advanced stage of the disease.

Human health risk The causative bacterium of paratuberculosis, M. avium ssp. paratuberculosis, is known to survive pasteurization of milk and other dairy products, and therefore could be a risk to human health. Increasing scientific evidence indicates that there is a link between paratuberculosis in dairy herds and Crohn's disease in humans. Crohn's disease is an incurable chronic inflammatory bowel disease.

Economic impact Paratuberculosis in domestic livestock may entail significant economic losses due to several factors, such as reduced production, premature culling, and veterinary costs. In the United States, paratuberculosis is of growing concern to the cattle industry because the presence of the disease impacts international marketing of cattle and cattle products, which causes economic losses to producers. Consequently, the Voluntary Johne's Disease Herd Status Program for Cattle (VJDHSP) has been established. In April of 2002, USDA-APHIS-Veterinary Service incorporated parts of this program into its national program standards.

Within the European Union, there are no official programs in place; however, country-specific policies apply. Australia has a National Johne’s Disease Control Program (NJDCP) that aims to reduce the spread and the impact of Johne’s disease. It is a cooperative program involving Australian livestock industries, government, and the veterinary profession. Animal Health Australia manages the program on behalf of these key stakeholders.

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Overview Bovine rotavirus is categorized within the Reoviridae viral family, and along with coronavirus, contributes to >50% of the diarrhea problems in calves. While rotavirus is common in cattle herds, other animals such as pigs, chickens, sheep, horses, and rabbits are also susceptible to the disease.

The virus enters through the small intestine, attacking villi and making it difficult for material to be effectively absorbed into the animal’s body. This condition leads to water loss from the epithelial cells and body, causing dehydration and potentially death if there is significant dehydration and emaciation.

Transmission generally occurs when an unaffected animal has oral contact with infected feces and contaminated feed, or if they are exposed to living quarters with poor hygiene characteristics. Cows displaying signs and symptoms may shed the virus for as long as a week, while some cows can become reinfected and shed the virus throughout their life and remain asymptomatic.

Signs The primary sign of rotavirus is a runny, often yellow diarrhea that contains mucous, blood, or both. Additionally, the animal may become lethargic and have a disinterest in drinking or feeding, which could result in mild to severe dehydration, depending on the animal and the circumstances.

Human health risk Bovine and human rotavirus strains are specific to their hosts and are not considered a transmission risk from one species to another.

Overview Salmonellosis is an infection caused by Salmonella bacteria. The presence of salmonellosis has been identified in countries throughout the world, but it appears to be most prevalent in areas of intensive animal husbandry, especially occurring in pigs, calves, and some types of poultry.

The disease can affect all domestic animals; however, young animals and pregnant or lactating animals are the most susceptible to the disease. The clinical signs that may be seen are abortion, arthritis, respiratory disease, and acute septicemia. Enteric disease, often presenting as a bloody, watery diarrhea with pyrexia, is the most common clinical manifestation.

Many animals, especially pigs, cattle and poultry, may also be infected but show no clinical illness. Such animals may be important in relation to the spread of infection between flocks and herds and also as a source of food contamination and human infections.

Signs Typical clinical signs can include fever and severe watery diarrhea with subsequent rapid onset of dehydration. The diarrhea is usually putrid and may contain blood and mucus. Salmonellae produce toxins that can contribute to gut damage and have systemic effects. If sufficient damage occurs to the intestinal lining, the bacteria may enter the bloodstream, resulting in septicemia, and the bacteria can spread to the brain, lungs, joints, uterus (causing abortion in pregnant cows), and other organs.

Human health risk Salmonellosis is one of the most important zoonotic diseases that can cause serious clinical symptoms in humans. Pigs, cattle, poultry, and eggs have been recognized as important sources of these Salmonella infections. The existence of this disease presents great risks for human health. Salmonella infections of animals intended for the food industry play an important role in public health, as these animals are considered to be the major source of human Salmonella infections.

Epidemiology The Schmallenberg virus belongs to the Bunyaviridae family, genus Orthobunyaviridae and is closely related to Akabane, Aino, and Shamonda viruses. This virus was first identified in November 2011 in Germany. It was found in several samples coming from bovine and ovine hosts showing atypical symptoms, not characteristic of known diseases at the time.

Signs This virus induces weak clinical symptoms affecting the global health of the animal, such as hyperthermia, loss of appetite, decreased milk production, and in some cases, diarrhea. Infection of female ruminants during gestation can also result in the birth of malformed animals (e.g., hydrocephalus).

Diagnostics Virus detection is optimally performed using the brain of an aborted fetus, but the virus can also be detected in blood, serum, and the spleen (FLI—German National Reference Laboratory).

Overview Trichomoniasis (Trich) is a venereal disease that occurs in cattle worldwide and is typically characterized by infertility and abortions in cows and heifers, which contributes to extended calving intervals.

The disease is caused by Tritrichomonas foetus (T foetus) a small, motile protozoan that lives in the reproductive tract of cows and the penis sheath of bulls. The disease organism is transferred to a cow's vagina from the bull during breeding and causes infection as it migrates to the uterus resulting in a white sticky discharge from the vulva of the infected cows.

When an infected bull is naturally bred with cows, 30%–90% become infected, which may suggest the existence of strain differences as well as a variation in breed susceptibility to the disease. Bulls of any age can remain infected for an indefinite period of time, but in younger males this scenario is less likely to occur. In contrast, cows are typically free of infection within 3 months of breeding, though they are still susceptible to reinfection. T foetus may also be transmitted when the semen from infected bulls is used during artificial insemination.

Signs The primary sign is infertility caused by embryonic death, which contributes to repeat breeding and scenarios where cows are in heat when they should be pregnant. In addition to reduced calving rates and calf crops being extended over 3-6 months and increased number of cows may be associated with nonpregnant abnormal reproductive diagnosis such as endometritis and pyometra. Bulls will display no signs of the T foetus but can shed the organism for an indefinite period of time. Diagnosis of the disease in bulls requires the collection and testing of a preputial fluid sample taken from the sheath of the bull's penis.

Human health risk It does not appear that Trichomoniasis presents a zoonotic risk.

Economic impact The economic losses associated with affected herds are primarily the result of smaller, less uniform calf crops, as well as increased culling, testing and prevention costs. Various studies and models have estimated income reduction anywhere between 20%-40% when trichomoniasis is present in a herd.

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